What are bellows used for?

I'm very new to MF photography, I apologize for the question and

also if it has already been asked before. What exactly are bellows

for? I'm asking because I just purchased a Pentacon 6, and it has

an optional bellows I can use. thanks..

Probably for macro/micro photography.

There are in general two kinds of bellows, those used for lens shades (on the subject side

of the lens) and those used for closeup/macro photography (between the lens and the

camera). Some also allow limited movements, but these are not as common in MF as in LF.

 

Taras

To extend the distance of lens to film plane, Macro-photography.

You could think of them as 'variable extension tubes'!

Bellows are also used on some cameras (like Mamiya RB/RZ 67) for simply focusing the lens -> altering the distance between the lens and the negative. There is nothing special that would limit the usage to macro photography. But as others said, optional bellows are usually meant for close up photography. Bellows are simply elastic light tight material. Quite clever and cheap innovation!

I shall assume that the bellows to which you are referring is not a lens hood. If you are shooting in MF, I expect you would know one from the other.

 

The explaination following referres to close-up (macro) phoptography. Have fun.

 

Extension Tubes and Bellows

 

Magnification is always a product of extension. The farther away from the film plane a lens is moved, the greater the magnification. To get life size magnification from any lens necessitates adding extension to the lens that is equal to its focal length. As a result, light intensity at the film plane is cut by 2 stops, which produces an aperture two stops less than that which appears in the LCD readout. Thus, a set aperture of f/11 can result in an effective aperture of f/22.

 

Corrected f/stop values can be calculated by multiplying the f/ stop marked on the lens by the actual lens to film distance and dividing the result by the focal length of the lens. Thus:

 

Marked f/ stop X actual lens to film dist

Focal length

 

To calculate a bellows extension factor, divide the square root of the bellows extension by the square of the focal length. Thus:

 

(bellows extension)2

(focal length)2

 

Exposure correction for magnification depends only upon magnification, not focal length. Accordingly, to determine exposure correction for any lens:

 

So, as above: M = focal length of primary ?i focal length of coupled lens.

M = 200 ?i 17

M = 11.7 or 12X

Where M is magnification ,

 

Therefore:

ECF = (M+1)2

Where ECF is Exposure Correction Factor

 

Alternatively, EF = (Image Distance (from the film plane)2

(Lens Focal length)2

 

EA = EF X Ap set on lens

Then EA is Effective Aperture

 

Bellows Extension and Effective lens aperture

So I could use bellows on Pentacon 6 and my 50mm Lens to do away with Telephotos? Or is it strictly for macro work? I've seen large format field cameras like a Tachihara with bellows and it's used mostly for landscape.

-->So I could use bellows on Pentacon 6 and my 50mm Lens to do away with Telephotos? Or is it strictly for macro work? I've seen large format field cameras like a Tachihara with bellows and it's used mostly for landscape.--<

 

No. Bellows on a fixed lens camera is used only for focusing. By moving the lens a far distance from the film you can focus up real close.

 

Bellows on a view camera not only allows the user to focus at any distance he chooses but also to use the swings and tilts aspect of the view camera to alter perpective , etc.